This invention is directed to novel compositions comprising one or more heptamantanes. This invention is also directed to novel processes for the separation and isolation of heptamantane components into recoverable fractions from a feedstock containing at least one or more heptamantane components.
The following publications and patents are cited in this application as superscript numbers:
1 Lin, et al., Natural Occurrence of Tetramantane (C22H28), Pentamantane (C26H32) and Hexamantane (C30H36) in a Deep Petroleum Reservoir, Fuel, 74(10):1512-1521 (1995)
2 Alexander, et al., Purification of Hydrocarbonaceous Fractions, U.S. Pat. No. 4,952,748, issued Aug. 28, 1990
3 McKervey, Synthetic Approaches to Large Diamondoid Hydrocarbons, Tetrahedron, 36:971-992 (1980).
4 Wu, et al., High Viscosity Index Lubricant Fluid, U.S. Pat. No. 5,306,851, issued Apr. 26, 1994.
5 Chung et al., Recent Development in High-Energy Density Liquid Fuels, Energy and Fuels, 13, 641-649 (1999).
6 Sandia National Laboratories (2000), World""s First Diamond Micromachines Created at Sandia, Press Release, (Feb. 22, 2000) www.Sandia.gov.
7 Balaban et al., Systematic Classification and Nomenclature of Diamondoid Hydrocarbonsxe2x80x94I, Tetrahedron. 34, 3599-3606 (1978).
8 Chen, et al., Isolation of High Purity Diamondoid Fractions and Components, U.S. Pat. No. 5,414,189 issued May 9, 1995.
All of the above publications and patents are herein incorporated by reference in their entirety to the same extent as if each individual publication or patent was specifically and individually indicated to be incorporated by reference in its entirety.
State of the Art
Heptamantanes are bridged-ring cycloalkanes. They are the face-fused heptamers of adamantane (tricyclo[3.3.1.13,7]decane). The compounds have a xe2x80x9cdiamondoidxe2x80x9d topology, which means their carbon atom arrangement is superimposable on a fragment of the diamond lattice (FIG. 1). Heptamantanes possess seven of the xe2x80x9cdiamond crystal unitsxe2x80x9d and therefore, it is postulated that there are one hundred sixty possible heptamantane structures. Among them, 85 of the one hundred sixty have the molecular formula C34H40 (molecular weight 448) and of these, 7 are symmetrical, having no enantiomers. Six have the molecular formula C32H36 (molecular weight 420) and 67 have the molecular formula C33H38 (molecular weight 434). There are two fully condensed heptamantanes having the molecular formula C30H34 (molecular weight 394).
Little or no published work is available for heptamantanes and higher molecular weight diamondoids. Heptamantane compounds have not been artificially synthesized or isolated and these compounds have been recently thought only to have a theoretical existence.7 Academic chemists have primarily focused research on the interplay between physical and chemical properties in lower diamondoids such as adamantane, diamantane and triamantane. Adamantane and diamantane, for instance, have been studied to elucidate structure-activity relationships in carbocations and radicals.3 Process engineers have directed efforts toward removing lower diamondoids from hydrocarbon gas streams.2 These compounds cause problems during the production of natural gas by solidifying in pipes and other pieces of equipment.
The literature contains little information regarding practical applications of higher diamondoids and even less, if any information regarding heptamantanes. This fact is probably due to extreme difficulties encountered in their isolation and due to failed synthesis attempts. Lin and Wilk, for example, discuss the possible presence of pentamantanes in a gas condensate and further postulate that hexamantane may also be present.1 The researchers postulate the existence of the compounds solely based on a mass spectrometric fragmentation pattern. They did not, however, report the isolation of a single pentamantane, hexamantane nor mention heptamantane. Nor were they able to separate non-ionized components during their spectral analysis. McKervey et al. discuss an extremely low-yielding synthesis of anti-tetramantane.3 The procedure involves complex starting materials and employs drastic reaction conditions (e.g., gas phase on platinum at 360xc2x0 C.). Although one isomer of tetramantane, i.e. anti-, has been synthesized through a double homologation route, these syntheses are quite complex reactions with large organic molecules in the gas phase and have not led to the successful synthesis of other tetramantanes. Similar attempts using preferred ring starting materials in accordance with the homologation route, have likewise failed in the synthesis of pentamantanes. Likewise, attempts using carbocation rearrangement routes employing Lewis acid catalysts, useful in synthesizing triamantane and lower diamondoids have been unsuccessful to synthesize other tetramantanes or pentamantanes. No attempt to synthesize or isolate heptamantanes has been reported.
Among other properties, diamondoids have by far the most thermodynamically stable structures of all possible hydrocarbons that possess their molecular formulas due to the fact that diamondoids have the same internal xe2x80x9ccrystalline latticexe2x80x9d structure as diamonds. It is well established that diamonds exhibit extremely high tensile strength, extremely low chemical reactivity, electrical resistivity greater than aluminum trioxide (Al2O3), excellent thermal conductivity, and superb optical properties.
In addition, based on theoretical considerations, the heptamantanes have sizes in the nanometer range and, in view of the properties noted above, the inventors contemplate that such compounds would have utility in micro- and molecular-electronics and nanotechnology applications. In particular, the rigidity, strength, stability, variety of structural forms and multiple attachment sites shown by these molecules makes possible accurate construction of robust, durable, precision devices with nanometer dimensions. The various heptamantanes are three-dimensional nanometer sized units showing different diamond lattice arrangements. This translates into a variety of rigid shapes and sizes for the one hundred sixty heptamantanes. For example, [121212] heptamantane is rod shaped, [12(3,4)12] heptamantane has a cross-shaped structure while [121234] is xe2x80x9cLxe2x80x9d shaped and [12132] is disc-shaped with one lobe. The two enantiomers of [121312] have left and right handed screw like structures. A variety of other shapes exist among the heptamantanes which may serve in applications which depend upon specific geometries. It has been estimated that MicroElectroMechanical Systems (MEMs) constructed out of diamond should last 10,000 times longer then current polysilicon MEMs, and diamond is chemically benign and would not promote allergic reactions in biomedical applications.6 Again, the inventors contemplate that the various heptamantanes would have similar attractive properties. Furthermore, most of the heptamantanes (molecular weight 448 as well as the partially condensed 420 and 434) possess chirality, offering opportunities for making nanotechnology objects of great structural specificity and ones which have useful optical properties. Applications of these heptamantanes include molecular electronics, photonic devices, nanomechanical devices, and nanostructured polymers and other materials.
Notwithstanding these advantages of heptamantanes, the art, as noted above, fails to provide for compositions comprising heptamantanes or for processes that would lead to these compositions. In view of the above, there is an ongoing need in the art to provide for compositions comprising one or more heptamantanes.
This invention is directed to novel compositions comprising one or more heptamantane components.
Accordingly, in one of its composition aspects, this invention is directed to a composition comprising one or more heptamantane components wherein said composition comprises at least about 25 weight percent heptamantane components based on the total weight of the diamondoids in the composition.
In another of its composition aspects, the compositions preferably comprise one or more heptamantane components wherein the heptamantane components make up from about 50 to 100 weight percent, preferably about 70 to 100 weight percent, more preferably about 90 to 100 weight percent and even more preferably about 95 to 100 weight percent of the total weight of the diamondoids in the compositions.
In another of its composition aspects, the compositions comprise at least about 10 weight percent and preferably at least about 20 weight percent of heptamantanes based on the total weight of the composition. Other compositions of this invention contain from 50 to 100 weight percent, 70 to 100 weight percent, 95 to 100 weight percent and 99 to 100 weight percent of heptamantanes based on the total weight of the composition.
In another of its composition aspects, the compositions preferably comprise from about 70 to 100 weight percent, more preferably from about 90 to 100 weight percent, even more preferably from about 95 to 100 weight percent and most preferably from about 99 to 100 weight percent of a single heptamantane component, including isolated optical isomers thereof, based on the total weight of the composition.
Compositions are sufficiently enriched in heptamantane components the heptamantanes can form crystal structures. Accordingly, another aspect of this invention is directed to a composition comprising a heptamantane crystal. Since such heptamantane can co-crystallize, another aspect of this invention is directed to the co-crystals comprising crystals of at least two heptamantane components or a heptamantane component and another higher diamondoid component.
This invention is also directed to novel processes for the separation and isolation of heptamantane components into recoverable fractions from a feedstock containing one or more heptamantane components and nonheptamantane materials. These processes for recovering a composition enriched in heptamantane components entail removing at least a portion of the nonheptamantane materials which have a boiling point below the lowest boiling heptamantane component and utilizing a subsequent separation technique to recover heptamantane components from the resulting residue. Accordingly, this aspect is directed to processes which comprise:
a) selecting a feedstock comprising recoverable amounts of heptamantane components and nonheptamantane materials;
b) removing from the feedstock a sufficient amount of nonheptamantane materials that have boiling points below the boiling point of the lowest boiling point heptamantane component in the feedstock under conditions to form a treated feedstock enriched in heptamantane components which can be recovered;
c) recovering heptamantane components by separating said treated feedstock formed in b) above with one or more additional separation techniques selected from the group consisting of chromatographic techniques, thermal diffusion techniques, zone refining, progressive recrystallization and size separation techniques.
In a preferred embodiment, after the step recited in b) the heptamantane components in the treated feedstock can be thermally treated to pyrolyze at least a sufficient amount of non-diamondoid components therefrom under conditions to provide a thermally treated feedstock retaining recoverable amounts of heptamantane. Such a pyrolization step prior to step c) is useful for thermally degrading at least a portion of any materials remaining in the treated feedstock having a thermal stability lower than the heptamantane components in common hydrocarbonaceous feedstocks. This pyrolysis step can be carried out in step b) if desired.
In a preferred embodiment of this invention, directed to the chromatographic techniques, is employing high performance liquid chromatography using one or more columns, more preferably reverse phase. A more preferred method, is using columns exhibiting a different selectivity to the heptamantane components slated for enrichment. Alternatively, high performance liquid chromatography can be coupled with gas chromatography, such as preparative gas chromatography to further facilitate isolations.